re PR tree-optimization/52424 (dom prematurely pops entries from const_and_copies stack)

2012-02-29  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>

	PR tree-optimization/52424
	* tree-ssa-dom.c (dom_opt_leave_block): Push a marker before
	calling dom_thread_across_edge.

From-SVN: r184662

gcc/ChangeLog

+2012-02-29  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
+
+	PR tree-optimization/52424
+	* tree-ssa-dom.c (dom_opt_leave_block): Push a marker before
+	calling dom_thread_across_edge.
+
 2012-02-29  Georg-Johann Lay  <avr@gjlay.de>
 
 	* config/avr/avr.c: Move definition of TARGET macros to end of file.

gcc/tree-ssa-dom.c

@@ -1779,6 +1779,9 @@ dom_opt_leave_block (struct dom_walk_data *walk_data, basic_block bb)
       && (single_succ_edge (bb)->flags & EDGE_ABNORMAL) == 0
       && potentially_threadable_block (single_succ (bb)))
     {
+      /* Push a marker on the stack, which thread_across_edge expects
+	 and will remove.  */
+      VEC_safe_push (tree, heap, const_and_copies_stack, NULL_TREE);
       dom_thread_across_edge (walk_data, single_succ_edge (bb));
     }
   else if ((last = last_stmt (bb))